“It was close. It was very tight, especially the tie-break in the first set. It was a lot of back and forth and I think I was very fortunate to win that set,” Zverev said. “It was a very close game, a few points here and there, but luckily I was able to come through.”

The left-handed German won 73 per cent of first-serve points, constantly attacking the net and staving off the World No. 90's strong returns to reach his third tour-level final. Zverev, who finished runner-up in Metz in 2010 and in Geneva last year, is into his first championship match on grass, on which he holds a 27-25 record according to the FedEx ATP Performance Zone.

He will enjoy it even more if he is able to lift his maiden trophy on Saturday. But Lukas Lacko, the 2012 Zagreb finalist who is also competing for his first title, stands in his way. The Slovakian advanced to his first ATP World Tour final for close to six-and-a-half years with a 6-3, 6-4 victory against fourth-seeded Italian Marco Cecchinato, fresh off his semi-final appearance at Roland Garros.

Lacko, who has grown in confidence since he recorded the biggest win of his career over World No. 11 Diego Schwartzman in the second round, lost just seven of his service points and struck nine aces for victory in 59 minutes at Devonshire Park. Now 7-7 in tour-level matches this season, he has also captured his 12th ATP Challenger Tour crown in Glasgow (d. Vanni). Cecchinato, the Gazprom Hungarian Open titlist (d. Millman), had not won a professional grass-court match prior to this week. He drops to 15-11 in 2018.

Lacko, who currently is World No. 94, is now projected to reach at least No. 73 on Monday, his highest position in the ATP Rankings since November 2013. He can climb even further with a win against Zverev, who won their only previous FedEx ATP Head2Head series meeting on grass in Halle last year.

“I hope it’s going to be a good match,” Zverev said. “This year, everything’s different. We’re meeting in the final, not the first round, and we’ll see what’s going to happen.”